The sky around Lagoon Nebula at true scale, north up and east left, with stars to magnitude 8. The circles show the field of a low-power eyepiece and of 10×50 binoculars.
Lagoon Nebula is a nebula w/cluster in Sagittarius, 4,340 light-years away
Lagoon Nebula (M8, NGC 6523, LBN 25, Sh2-25, RCW 146, Gum 72) is a nebula w/cluster in the constellation Sagittarius, 4,340 light-years away. It shines at magnitude 5.8 and spans 2.5° × 40′ of sky, about 189 light-years across. It is an easy target in binoculars, and it is highest in the evening sky in August.
Nebula: a cloud of gas and dust. Emission nebulae glow on their own, lit by ultraviolet light from hot young stars; reflection nebulae shine by starlight scattered from dust; dark nebulae block the light behind them.
Lagoon Nebula is Sh2-25 in the Sharpless catalog
Stewart Sharpless listed it in his catalog of H II regions (1959), drawn from the red and blue prints of the Palomar Sky Survey. He rated each region's brightness on a scale of 1 to 3; Sh2-25 is bright (class 3 of 3). It is also listed as RCW 146, LBN 25, Gum 72.
Lagoon Nebula is RCW 146 in the RCW catalog of southern H-alpha regions
Lagoon Nebula lies 5.6° west of Kaus Borealis, the magnitude 2.8 star. Three fingers held at arm's length cover about 5°.
Lagoon Nebula is highest in the evening in August
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole southern hemisphere and north to about 66°N, and never sets south of 66°S.
Lagoon Nebula is 4,340 light-years away
The light seen from Lagoon Nebula tonight left it about 4,340 years ago. It ranks 27 of 109 by distance among the 110 Messier objects. Distance source: Gaia cluster distance (NGC 6530), Gaia-ESO A&A 2024.
